The pcd file show a strange angel

[Richardcvpr]

when i put the pcd file generate by the program in the rviz, it have a strange angle, i have no ideal why the PCD file is not parallel to the ground grid that needs to be projected, and the entire PCD file may flip at strange angles.

[TianzeXie]

I think the reason is the global cordinate system is fixed on the first frame，which means the pose of poind cloud depends on the first frame's pose